1. Field of the Invention
The present invention relates to a catalytic process for alkylation of aromatic hydrocarbon compounds.
2. Background of the Art
Alkylation of aromatic compounds with olefins has been used in the production of many important chemicals or petrochemical products or intermediates, such as ethylbenzene for polystyrene polymer, cumene for phenol synthesis, and long chain alkylbenzene for the detergent industry. Generally, catalysts are used in these processes to enable the chemical reaction to occur at milder conditions (e.g. low temperatures and/or low pressures) in addition to make the reaction more selective toward desired products.
In 1965 the preparation of cumene by the reaction of benzene with propylene, using zeolite X or Y as catalyst, was first described [Minachev, Kr. M., et al, Neftekhimiya 5 (1965) 676]. Venuto et al (J. Catal. 5, (1966) 81) subsequently described faujasitic zeolite catalysts for the alkylation of benzene with light olefins. U.S. Pat. No. 4,292,458 describes the use of ZSM-5 type zeolites for alkylating benzene with ethylene. At present, the commercial benzene alkylation processes with ethylene or propylene in liquid phase often use zeolite beta as the alkylation catalyst (e.g. U.S. Pat. No. 4,891,458).
U.S. Pat. No. 5,015,786 describes benzene alkylation with isopropanol catalyzed by zeolite Y.
In U.S. Pat. No. 5,160,497, a dealuminated zeolite Y is used with a molar ratio ranging from 8 to 70 for the alkylation of benzene with propylene and/or isopropanol.
Preparation of monoalkylated aromatic hydrocarbon by the transalkylation of polyalkylated aromatic hydrocarbons with aromatic substrates in which zeolite catalysts with small, medium and large pores are used, are described in U.S. Pat. No. 3,385,906, U.S. Pat. No. 4,169,111 and EP 308,097.
EP 439,632, EP 687,500 and EP 847,802 describe the production of monoalkylated aromatic hydrocarbons from aromatic hydrocarbon substrates, not only by means of alkylation, but also by means of transalkylation and a combined alkylation and transalkylation process, catalyzed by zeolite beta. In particular, reactions described include alkylation of benzene with ethylene or propylene and the transalkylation of diethylbenzene or diisopropylbenzene with benzene.
U.S. Pat. No. 6,809,055 B2 entitled “Zeolites and Molecular Sieves and the Use Thereof” discloses controlled conditions to remove the organic template in template-containing zeolites to achieve a higher acidity and more active catalyst than the catalyst produced using conditions in existing commercial production of zeolites.
A specially prepared zeolite beta (i.e., high performance zeolite beta), disclosed in the above-mentioned patent application, has the ratio of strong acid sites to weak acid sites greater than 1.0 and is more active than conventional zeolite beta. As a critical step in the preparation of high performance zeolite beta, template removal by mild calcination can be implemented relatively easily at small scale either by spreading the zeolite bed thinner over a tray during calcinations, or using a very slow heating rate combined with high air circulation to minimize formation of “hot spots” in the catalyst bed.